Each month of the year is traditionally associated with a gemstone. For those born in May your birthstone is emerald, one of the most highly valued and mystical gemstones. This precious gemstone has been characterised throughout history as being the 'greenest green' – greener than even the most luscious landscapes. The name is derived from the ancient Greek word smaragdos which means 'green stone'. Cleopatra was said to have a passion for this gemstone and favoured it above all others.